Watsi, “an online peer-to-peer crowdfunding platform that allows users to fund life-changing medical treatments for underserved people in developing countries”, has become the first nonprofit that the start-up incubator Y Combinator has chosen to invest in.

Perhaps one of the reasons that Watsi are the first non-profit to become part of Y Combinator is because at Watsi, 100% of your donations directly fund medical treatments. As Paul Graham explains:

Watsi.org is separately funded. They pay all their operational costs from their own funding, and none from your donations. They even eat the credit card processing fees. So when you donate to Watsi, you never have the uncomfortable feeling that lots of your money will be eaten up by administrative costs. Your money has impact you can measure.

This is a similar model to Charity: Water, who ensure all donations go 100% to water aid projects, with their operating costs covered by private donors.